Detection rules › Sublime MQL

Link: Multistage Landing - Abused Buildin.ai

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

Analyzes shared content links from buildin.ai domain that contain credential harvesting language with medium to high confidence in the display text.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesFree file host, Social engineering

Event coverage

Rule body MQL

type.inbound

// filter to just buildin.ai
and any(filter(body.links,
               (
                 .href_url.domain.root_domain == "buildin.ai"
                 and strings.icontains(.href_url.path, '/share')
               // inspect display text
               )
        ),
        any(ml.nlu_classifier(ml.link_analysis(., mode="aggressive").final_dom.display_text
            ).intents,
            .name == "cred_theft" and .confidence in ("medium", "high")
        )
)

Detection logic

Scope: inbound message.

Analyzes shared content links from buildin.ai domain that contain credential harvesting language with medium to high confidence in the display text.

  1. inbound message
  2. any of filter(body.links) where:
    • any of ml.nlu_classifier(ml.link_analysis(., mode='aggressive').final_dom.display_text).intents where all hold:
      • .name is 'cred_theft'
      • .confidence in ('medium', 'high')

Inspects: body.links, body.links[].href_url.domain.root_domain, body.links[].href_url.path, type.inbound. Sensors: ml.link_analysis, ml.nlu_classifier, strings.icontains.

Indicators matched (5)

FieldMatchValue
body.links[].href_url.domain.root_domainequalsbuildin.ai
strings.icontainssubstring/share
ml.nlu_classifier(ml.link_analysis(filter(body.links)[], mode='aggressive').final_dom.display_text).intents[].nameequalscred_theft
ml.nlu_classifier(ml.link_analysis(filter(body.links)[], mode='aggressive').final_dom.display_text).intents[].confidencemembermedium
ml.nlu_classifier(ml.link_analysis(filter(body.links)[], mode='aggressive').final_dom.display_text).intents[].confidencememberhigh